Abstract: In order to obtaion the reasons for polyurethane grouting reinforcement materials burning problems applied in underground coal mine, this paper carried on large volume grouting experiment with polyurethane grouting reinforcement materials, to test that inner side maximum reaction temperature and to analysis the inner side features after reaction. The experiment results showed that the inner side maximum reaction temperature in the large volume grouting model were much higher tha n the lab testing maximum reaction temperature according to the AQ 1089- -2011 standard tested maximum temperature about 140 °C when adding 1% water into the p olyurethane grouting reinforcement materials. Some products maximum reaction temperature even reached over 340 °C resulting that coal spontaneous combustion.Wh ereas in the same case, the maximum reaction temperature of pure-polyurethane grouting reinforcement materials was about 165。Cwithout any spontaneous combustio n signs and sodium silicate modified polyurethane grouting reinforcement materials was only no less than102。C. All results indicated that pure-polyurethane grouting re inforcement materials and sodium silicate modified polyurethane grouting reinforcement materials grouted in the coal mine should be safety without any burning proble ms.